Tube coupling

ABSTRACT

A fluid coupling having an outer housing with an internal bore, an O-ring fitted within the bore, a spacer bushing fitted against the O-ring, a gripper ring fitted against the axially outer side of the spacer ring, the gripper ring having axially and radially inwardly protruding circumferentially spaced gripping teeth, and an end bushing holding the gripper ring, spacer bushing, and O-ring within the outer housing. A second gripper ring and a second spacer ring are used in some embodiments.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. Ser. No.11/764,712 filed Jun. 18, 2007, which is a continuation of U.S. Ser. No.11/061,139 filed Feb. 18, 2005 and issued Jun. 19, 2007 as U.S. Pat. No.7,232,159, which is a continuation of U.S. Ser. No. 10/266,935 filedOct. 7, 2002 and issued Mar. 1, 2005 as U.S. Pat. No. 6,860,523, whichis a continuation of U.S. Ser. No. 09/570,846 filed May 12, 2000 andissued Oct. 15, 2002 as U.S. Pat. No. 6,464,266, which is acontinuation-in-part of U.S. Ser. No. 09/425,909 filed Oct. 21, 1999(now abandoned) and a continuation-in-part of U.S. Ser. No. 09/216,376filed Dec. 18, 1998 (now abandoned), and claims the benefit ofPCT/US99/30149, filed Dec. 17, 1999, which applications are incorporatedherein by reference in their entirety.

TECHNICAL FIELD

This invention pertains to removable couplings of the type for securinga plastic or copper tube by pressing on the tube without the need forwelding or solder.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 4,911,406 shows a tube coupling in which a metal orplastic tube can be coupled in a fluid-tight connection to a valve orthe like simply by pressing the tube into the coupling. The tube is heldinto the coupling by a flexible gripper ring having teeth, which biteinto the tube to prevent the tube from being pushed out by the fluidpressure in the coupling. The teeth are arranged such that the tube canbe removed from the coupling by unscrewing the coupling but cannot beremoved simply by axially pulling the tube without rotation of the tube.An O-ring seal is provided to prevent leakage of fluid outside of thecoupling around the tube.

One of the advantages of the invention of the U.S. Pat. No. 4,911,406 isthat by screwing the tube out of the gripper ring there is minimaldamage to the surface of the tube. This then enables other advantageousarrangements of the seal and the gripper ring within the coupling. Withthe introduction of softer plastic tubing, such as, polybutylene or PEX(cross-linked polyethylene, plastic) to the plumbing industry, thedemands on the holding power of the gripper ring have increased. Thesofter tubing material can cause the teeth of the gripper ring to gougegrooves in the tubing when the tubing is subjected to high numbers ofrepeated cycles at higher hydrostatic pressures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an axial section of the coupling embodying the principles ofthe invention.

FIG. 2 is an exploded view of the coupling shown in FIG. 1.

FIG. 3 is a fragmentary section of the gripper ring showing one of thegripper teeth.

FIG. 4 is a generic illustration of what could be a test cap or a valveor other coupling device product embodying the principles of theinvention.

FIG. 5 shows the O-ring seal and gripper ring arrangement of thisinvention within the valve of the type shown in U.S. Pat. No. 4,911,406.

FIG. 6 is an axial section of the coupling embodying the principles ofthe invention with multiple gripper rings for use, for example, with avalve.

FIG. 7 is an exploded view of the coupling shown in FIG. 6.

FIG. 8 is a fragmentary section of the gripper ring showing one of thegripper teeth.

FIG. 9 is a generic illustration of uses for the coupling with whatcould be a valve, a shower head, a tub faucet coupling, a tube coupling,or any other application or use for this unique coupling.

FIG. 10 shows another embodiment of the invention with three gripperrings. This view is intended to show that the number of gripper ringscan be any multiple of two or more.

FIG. 11 shows still another embodiment of the coupling used for a testcap. These various views are intended to show that the coupling has awide variety of uses and configurations not all of which are shown forpurposes of brevity.

FIG. 12 shows another embodiment of the coupling.

FIG. 13 shows another embodiment in which a valve using the push-oninvention is used to replace a conventional metal valve with its normalcompression ring.

DETAILED DESCRIPTION OF THE INVENTION

One improvement described herein is the reverse position of a gripperring in the coupling from the position shown in the U.S. Pat. No.4,911,406. In the illustrated embodiments with this improvement, theseal, such as an O-ring seal, is arranged axially inward of the gripperring in the outer housing of the coupling. This is followed by a spacerbushing which holds the ring in place and the gripper ring, with itsteeth, is on the axially outer side of the spacer bushing. This enablesthe detection of a leak caused by inadequately inserting a tube into theO-ring seal. It is particularly advantageous also in the situation ofre-piping or replacing a previous metal valve to enable the existingcompression ring used with metal vales to fit into a valve using thisgripper ring arrangement.

Another improvement described herein over U.S. Pat. No. 4,911,406 is theprovision of two or more gripper rings for increasing the holding powerof the rings in the coupling for use with the softer tubing. The two ormore gripper rings co-act on the tubing in a synergistic effectdistributing the load between them to substantially increase the holdingpower of the rings in the softer tubing. It is believed that thesoftness of the tubing allows movement of the teeth in the plastic untilthe load on the rings is distributed over more of the rings thusincreasing the ultimate holding power of the rings.

Other embodiments are illustrated and described herein.

As best shown in FIG. 1, the unique coupling is shown in one form as ageneric coupling but could be a test cap. A test cap, for example, isused in the plumbing industry for checking temporarily on the pressureof a plumbing system to see if all of the joints are free from leaks andthat the proper pressure may be maintained. Usually then the test cap isremoved and a permanent valve soldered or bonded onto the tube. The manyapplications for the coupling is further shown generically in phantomlines in FIG. 4, in which the phantom line box is a test cap coupling, avalve, an end unit like a shower-head, a coupling for joining two piecesof tubing together, etc. FIG. 5 shows more specifically the inventionfor the valve. The details of these different applications are obviousto one of ordinary skill in the art and the details of U.S. Pat. No.4,911,406 are incorporated herein by reference thereto.

In all of the couplings of FIGS. 1-5, the invention includes an outerhousing 10 having an inner bore 12 with a side wall 14. The inner borehas a seal support surface 16 against which is fitted a conventionalO-ring seal 15. The seal is held in the bore by a spacer bushing 18. Thespacer bushing has circumferentially spaced axial grooves 33, as bestshown in FIG. 2. A metallic gripper ring 27 is provided withcircumferentially spaced axially and radially inwardly protruding teeth29. The spacer bushing has a flat 36 aligned with a flat 30 on thegripper ring 27. The inside wall of the housing has a protruding flat 31to receive the flats on the bushing and gripper ring. The gripper ringis also provided with a notch 39 and the spacer bushing provided with anotch 41, which notches engage a protrusion 40 (FIG. 1) on the insidewall 14 of the outer housing 10. The flats on the inner bushing and thegripper ring and the notches are provided to assure proper installationof the gripper ring and inner bushing within the housing.

An end bushing 20 is positioned against the gripper ring and holds theO-ring, spacer bushing, and gripper ring tightly together so that theteeth of the gripper ring extend into the inner bore 12. The end bushingis held within the internal bore of the outer housing 10 by sonic welds22. The end bushing has a passageway 24 provided with guide ribs 28 forguiding a plastic or copper tube 26 into the coupling. The tube endinserted into the coupling is shown in phantom lines in FIG. 1. Innerribs 35 are provided in the side wall 14 of the internal inner bore 12.In general, the gripper ring is made from a full hard stainless steel,the coupling parts from plastic, such as, acetal, or for largercouplings, metal, and the tubes or pipe made from copper or conventionalPVC used in plumbing polybutylene, CPVC, PEX or other metals andplastics used in plumbing.

As best shown in FIG. 1, the coupling is assembled by placing the O-ringagainst the ring support surface 16, the spacer bushing is aligned withits flat 36 against the flat 31 of the outer housing and slid into placeagainst the O-ring, the gripper ring is then placed against the spacerbushing with its flat 30 aligning the teeth 29 into the grooves 33 ofthe spacer bushing. Then the end bushing is placed within the outerhousing and welded into place by sonic welding 22. For metal couplings,the outer housing can be secured by any suitable permanent attachmentsuch as crimped or interfering threads. When a tube 26 is to be insertedin the coupling or the coupling inserted over a tube, the tube and thecoupling are moved axially to one another with the tube engaging theteeth. The teeth extend into the inner bore of the housing a distancefurther than the outer diameter of the tube 26 so that the teeth aredeflected by the tube as the tube and housing are moved axially to oneanother. This creates an immediate gripping engagement of the teeth evenbefore any fluid pressure is applied in the coupling. The tube isinserted until it tightly engages the end wall 50 of the bore 12. Thiscan be felt by the user of the coupling since the tube can be pushed tomove axially, albeit tightly, until the end of the tube stops againstthe end wall 50 and cannot be pushed any further relative to the outerhousing.

The O-ring seal maintains the fluid seal around the tube. The tubecannot be solely axially withdrawn by fluid pressure without destroyingthe coupling and will maintain quite a high fluid pressure. The tube canbe removed by unscrewing the coupling relative to the tube. The teeth 29in the gripper ring can be manufactured with a slight twist or by usingthe full hard stainless steel or equivalent material, such as manganese,or composites, and a ring thickness of no greater than about 0.012inches, preferably 0.008 inches, then the twist can be created by theforces acting on the teeth as the tube 26 is simultaneously rotated andpulled out of the housing. By rotating the tube while pulling, edges ofthe gripper teeth will move within the grooves 30 causing friction onone edge of the teeth allowing the teeth to twist and the tube screw outof the gripper ring. If the tube is initially not inserted past thegripper ring, or is not inserted through the O-ring seal, leakage willbe apparent almost immediately when the pressure is applied to theplumbing system. Thus, an advantage of this embodiment is it gives animmediate visual check on the proper placement of the tube within thecoupling or the position of the test cap over the coupling.

FIG. 4 shows a phantom version of a coupling to illustrate that thecoupling could be a test cap as shown in FIG. 1, a valve in U.S. Pat.No. 4,911,406, or simply a mirror image of the right side coupling 50being on the left side to simply join two tubes together.

FIG. 5 shows an embodiment using the valve or housing 50 a of U.S. Pat.No. 4,911,406 as the coupling. Another advantageous feature of theinvention is illustrated in FIG. 5 by showing that pre-cut lengths oftubing or hose 60 can be bonded and crimped as at 61 or otherwisepermanently secured to the valve to provide a complete connection fromthe plumbing system to an appliance or other plumbing fixture. Thus,installation can be made more economically and faster having a completepre-cut plumbing connection already made-up and available.

As best shown in FIG. 6, the unique coupling is shown with multiplegripper rings in one form as a valve. However, while a valve has beenshown in the embodiment of FIG. 6, this is for illustration purposesonly and the coupling can be used for a valve, such as shown in U.S.Pat. No. 4,911,406 or any other use for a coupling. This is showngenerically in phantom lines in FIG. 9, in which the phantom line box isa valve, a coupling for joining two pieces of tubing together, a showerhead, a tub faucet coupling, or any other use where a soft tubularplumbing material is to be joined to more tubing or to some plumbingfixture. These different applications or uses for the coupling areobvious to one of ordinary skill in the art and the details of U.S. Pat.No. 4,911,406 are incorporated herein by reference thereto.

In the couplings of FIGS. 6-11, the invention includes an outer housing110 having an inner bore 112 with a side wall 114. The inner bore has aseal support surface 116 against which is fitted a conventional O-ringseal 115. The seal is held in the bore by a spacer bushing 118. Thespacer bushing has circumferentially spaced axial grooves 133, as bestshown in FIG. 7. A metallic gripper ring 127 is provided withcircumferentially spaced axially and radially inwardly protruding teeth129. A second identical gripper ring 132 is provided against the O-ringseal and thus on the opposite side of the spacer bushing 118. The spacerbushing has a flat 136 aligned with a flat 130 on the gripper rings 127,132. The inside wall of the housing has a protruding flat 131 to receivethe flats on the bushing and gripper rings. The gripper rings are alsoprovided with a notch 139 and the spacer bushing provided with a notch141, which notches engage a protrusion or key 140 (FIG. 6) on the insidewall 114 of the outer housing 110. The flats on the inner bushing andthe gripper rings and the notches are provided to assure properinstallation of the gripper rings and inner bushing within the housing.

An end bushing 120 is positioned against the gripper ring 127 and holdsthe O-ring, spacer bushing, and gripper rings tightly together so thatthe teeth of the gripper rings extend into the inner bore 112. The endbushing is held within the internal bore of the outer housing 110 bysonic welds 122 (FIG. 10). The end bushing is provided with an innerbore 124 and protruding guide ribs 128 for guiding a plastic or coppertube 126 into the coupling. In the alternative, these ribs can beeliminated so that existing old repaired plumbing tubing with existingferrules can be fitted into larger diameter of the end bushing 120 as inFIG. 13. The tube end inserted into the coupling is shown in FIG. 6.Inner ribs 135 (FIG. 7) are provided in the side wall 114 of theinternal inner bore 112. In general, the gripper rings are made from afull hard stainless steel, the coupling parts from plastic, such as,acetal, or for larger couplings, metal, and the tubes or pipe made fromcopper, conventional PVC, polybutylene, PEX, or other metals andplastics used in plumbing.

As best shown in FIG. 6, the coupling is assembled by placing the O-ringagainst the ring support surface 116, the gripper ring 132 is placedagainst the O-ring, the spacer bushing is aligned with its flat 136against the flat 131 of the outer housing and slid into place againstthe gripper ring 132, the gripper ring 127 is then placed against theopposite side of the spacer bushing with its flat 130 aligning the teeth129 into the grooves 133 of the spacer bushing. Then the end bushing isplaced within the outer housing and welded into place by sonic welding122. For metal couplings, the outer housing can be secured by anysuitable permanent attachment such as crimped or interfering threads.When a tube 126 is to be inserted in the coupling or the couplinginserted over a tube, the tube and the coupling are moved axially to oneanother with the tube engaging the teeth. The teeth of both rings extendinto the inner bore of the housing a distance further than the outerdiameter of the tube 126 so that the teeth are deflected by the tube asthe tube and housing are moved axially to one another. This creates animmediate gripping engagement of the teeth even before any fluidpressure is applied in the coupling. The tube is inserted until ittightly engages the end wall 150 (FIG. 10) of the bore 112. This can befelt by the user of the coupling since the tube can be pushed to moveaxially, albeit tightly, until the end of the tube stops against the endwall 150 and cannot be pushed any further relative to the outer housing.

The O-ring seal maintains the fluid seal around the tube. The tubecannot be solely axially withdrawn by fluid pressure without destroyingthe coupling and will maintain quite a high fluid pressure. The tube canbe removed by unscrewing the coupling relative to the tube, althoughwith softer plastic tubing the teeth may dig into the tubing more deeplyand the gouged surface of the tubing may be damaged when the coupling isunscrewed. In this case, a new tube may be needed or the damaged sectionof the original tube can be cut-off and the remaining undamaged end ofthe tubing can then be re-inserted into the coupling. The teeth 129 inthe gripper rings can be manufactured with a slight twist or by usingthe full hard stainless steel or equivalent material, such as manganese,or composites, and a ring thickness of no greater than about 0.012inches, preferably 0.008 inches, then the twist can be created by theforces acting on the teeth as the tube 126 is simultaneously rotated andpulled out of the housing. By rotating the tube while pulling, edges ofthe gripper teeth will move within the grooves 130 causing friction onone edge of the teeth allowing the teeth to twist and the tube screw outof the gripper ring.

In the embodiments shown, if the tube is initially not inserted past thegripper ring, or is not inserted through the O-ring seal, leakage willbe apparent almost immediately when the pressure is applied to theplumbing system. Thus, an advantage of this embodiment is it gives animmediate visual check on the proper placement of the tube within thecoupling or the position of the valve over the coupling.

FIG. 8 shows a typical gripper ring.

FIG. 9 shows a phantom version of a coupling to illustrate that thecoupling could be a valve, a coupling joining two tubes, a faucetcoupling, a shower head, a test cap, or any other plumbing fixture usinga push on coupling.

FIG. 10 shows another embodiment with the same features of the inventionbut with more gripper rings (three, namely, 127, 177, and 187 beingshown) and more spacers 118, 178, and 188.

FIG. 11 shows an embodiment using the coupling as a test cap. A test capis used in a plumbing system to see if all of the joints are free fromleaks and that the proper pressure may be maintained. Usually then thetest cap is removed and a permanent cap soldered or bonded onto thetube.

FIG. 12 shows another embodiment similar to FIGS. 10 and 11 but with aspacer 118 a placed between the o-ring and the gripper ring.

FIG. 13 shows a valve having an O-ring seal 115 and one or more gripperrings, preferably two, such as, gripper rings 130 and 132. The endbushing in this embodiment is tapered internally as at 210 so that themetal compression ring 202 of a conventional metal threaded compressiontype valve fitting can fit into the taper 210 and allow the end of thepipe with the compression ring left intact on the pipe, pushed into thevalve until it is past the O-ring seal and with the compression ringabutting the tapered surface of the end bushing. In this embodiment, thepush-on valve of this invention replaces the conventional screw oncompression fitted valve. The compression nut 200 from the old valve maybe left on the pipe exposed or can be pushed back into the hole in thewallboard where it is hidden. The location of the O-ring axially inwardof the gripper rings is advantageously employed in this re-pipingembodiment because it allows the free end of the pipe of the replacedpipe fitting to be inserted far enough into the valve to pass inside theO-ring and be effectively sealed even though the end of the pipe may notreach the end of the internal bore 112 when the compression ring engagesthe tapered surface 210 of the end bushing. The gripper rings will, ofcourse, hold the pipe in the valve and within the O-ring seal.

While two and three gripper rings have been shown in the drawing, anymultiple of gripper rings can be used within the spacing of thecoupling.

While the preferred embodiments have been illustrated and described, itshould be apparent that variations will be apparent to one skilled inthe art. Accordingly, the invention is not to be limited to the specificembodiments shown in the drawings.

1. A coupling for holding a tube therein, comprising: an outer housinghaving an internal bore with a circumferential side wall, a sealretained against axial movement within said internal bore in fluid-tightengagement with said housing and positioned for fluid-tight engagementwith the tube when positioned within said internal bore, a non-movablefirst spacer bushing retained against axial movement within saidinternal bore and having an axially inner side and an axially outerside, a non-movable second spacer bushing retained against axialmovement within said internal bore and having an axially inner side andan axially outer side, a first gripper ring located axially outward ofsaid seal and having a non-movable peripheral portion retained againstaxial movement within said internal bore, said first gripper ringfurther including gripper teeth extending inwardly from said peripheralportion of said first gripper ring and positioning inner edges of saidgripper teeth stationary within said internal bore in position awaitingengagement with the tube when positioned within said internal borewithout adjusting movement of said first gripper ring, said peripheralportion of said first gripper ring lying adjacent and between saidaxially outer side of said first spacer bushing and said axially innerside of said second spacer bushing, and a second gripper ring locatedaxially outward of said second spacer bushing and having a non-movableperipheral portion retained against axial movement within said internalbore, said second gripper ring further including gripper teeth extendinginwardly from said peripheral portion of said second gripper ring andpositioning inner edges of said gripper teeth stationary within saidinternal bore in position awaiting engagement with the tube whenpositioned within said internal bore without adjusting movement of saidsecond gripper ring, said peripheral portion of said second gripper ringlying adjacent said axially outer side of said second spacer bushing. 2.The coupling of claim 1 wherein said first spacer bushing has an axiallyinward seal engagement portion in engagement with said seal to retainsaid seal in position in said housing.
 3. The coupling of claim 1further including an end bushing attached to said housing and retainingsaid first and second spacer bushings and said peripheral portions ofsaid first and second gripper rings stationary in said internal boreagainst axial movement.
 4. The coupling of claim 1 wherein said gripperteeth of said first and second gripper rings are held stationary withinsaid internal bore except for movement produced by engagement with thetube.
 5. The coupling of claim 1 wherein said non-movable firstperipheral portion of said first gripper ring holds said gripper teethof said first gripper ring in fixed stationary positions without radialor axial movement thereof required to position said gripper teeth ofsaid first gripper ring for engagement with the tube, and saidnon-movable second peripheral portion of said second gripper ring holdssaid gripper teeth of said second gripper ring in fixed stationarypositions without radial or axial movement thereof required forengagement with the tube.
 6. The coupling of claim 1 wherein said firstspacer bushing has a support surface toward said axially outer sidethereof and said gripper teeth of said first gripper ring engage saidsupport surface of said first spacer bushing, and said second spacerbushing has a support surface toward said axially outer side thereof andsaid gripper teeth of said second gripper ring engage said supportsurface of said second spacer bushing, said gripper teeth of said firstgripper ring extend radially inward beyond said support surface of saidfirst spacer bushing and are retained in position to engage the tubewhen positioned within said internal bore without adjustment of theposition of said first spacer bushing or first gripper ring within saidinternal bore, and said gripper teeth of said second gripper ring extendradially inward beyond said support surface of said second spacerbushing and are retained in position to engage the tube when positionedwithin said internal bore without adjustment of the position of saidsecond spacer bushing or second gripper ring within said internal bore.7. The coupling of claim 1 wherein said first spacer bushing has aninterior wall defining an aperture sized and positioned to receive thetube therethrough when the tube is positioned within said internal bore,and said second spacer bushing has an interior wall defining an aperturesized and positioned to receive the tube therethrough when the tube ispositioned within said internal bore, said gripper teeth of said firstgripper ring protrude inwardly beyond said interior wall of said firstspacer bushing in position to engage the tube when positioned withinsaid aperture of said first spacer bushing without adjustment of theposition of said first spacer bushing or first gripper ring within saidinternal bore, and said gripper teeth of said second gripper ringprotrude inwardly beyond said interior wall of said second spacerbushing in position to engage the tube when positioned within saidaperture of said second spacer bushing without adjustment of theposition of said second spacer bushing or second gripper ring withinsaid internal bore.
 8. The coupling of claim 1 wherein said first spacerbushing has a support surface toward said axially outer side thereof andsaid gripper teeth of said first gripper ring are held stationaryagainst said support surface of said first spacer bushing prior toengagement with the tube, and said second spacer bushing has a supportsurface toward said axially outer side thereof and said gripper teeth ofsaid second gripper ring are held stationary against said supportsurface of said second spacer bushing prior to engagement with the tube.9. The coupling of claim 1 wherein said gripper teeth of said firstgripper ring extending radially inward beyond said first spacer bushingand said gripper teeth of said second gripper ring extending radiallyinward beyond said second spacer bushing, said gripper teeth of saidfirst and second gripper rings being held in stationary non-retractableposition within said internal bore, whereby at all times said gripperteeth of said first and second gripper rings are held ready to engagethe tube without prior adjusting movement of said first and secondgripper rings by a user of the coupling.
 10. The coupling of claim 1wherein said gripper teeth of said first and second gripper rings areheld in stationary non-retractable position within said internal bore inposition at all times to engage the tube when positioned within saidinternal bore.
 11. A coupling for holding a tube therein, comprising: anouter housing having an internal bore with a circumferential side wall,said internal bore being sized to receive the tube therein, anon-movable first spacer bushing retained against axial movement withinsaid internal bore and having an axially inner side and an axially outerside, a non-movable second spacer bushing retained against axialmovement within said internal bore and having an axially inner side andan axially outer side, a first gripper ring having a non-movableperipheral portion retained against axial movement within said internalbore, said first gripper ring further including gripper teeth extendinginwardly from said peripheral portion of said first gripper ring andpositioning inner edges of said gripper teeth stationary within saidinternal bore in position awaiting engagement with the tube whenpositioned within said internal bore without adjusting movement of saidfirst gripper ring, said peripheral portion of said first gripper ringlying adjacent and between said axially outer side of said first spacerbushing and said axially inner side of said second spacer bushing, and asecond gripper ring having a non-movable peripheral portion retainedagainst axial movement within said internal bore, said second gripperring further including gripper teeth extending inwardly from saidperipheral portion of said second gripper ring and positioning inneredges of said gripper teeth stationary within said internal bore inposition awaiting engagement with the tube when positioned within saidinternal bore without adjusting movement of said second gripper ring,said peripheral portion of said second gripper ring lying adjacent saidaxially outer side of said second spacer bushing.
 12. A coupling forholding a tube therein, comprising: a outer housing having an internalbore with a circumferential side wall, a seal in said internal bore influid-tight engagement with said housing and positioned for fluid-tightengagement with the tube when positioned within said internal bore, anon-movable first spacer bushing retained against axial movement withinsaid internal bore and having an axially inner side and an axially outerside, a non-movable second spacer bushing retained against axialmovement within said internal bore and having an axially inner side andan axially outer side, a first gripper ring located axially outward ofsaid seal and held in a fixed axial position between said axially outerside of said first spacer bushing and said axially inner side of saidsecond spacer bushing, said first gripper ring having non-retractablegripper teeth with inner edges protruding inwardly into said internalbore sufficient to engage the tube when positioned within said internalbore, and a second gripper ring held in a fixed axial position adjacentsaid axially outer side of said second spacer bushing, said secondgripper ring having non-retractable gripper teeth with inner edgesprotruding inwardly into said internal bore sufficient to engage thetube when positioned within said internal bore.
 13. A coupling forholding a tube therein, comprising: a housing having an internal borewith a circumferential side wall, said internal bore being sized toreceive the tube therein, a non-movable first spacer bushing retainedagainst axial movement within said internal bore and having an axiallyinner side and an axially outer side, a non-movable second spacerbushing retained against axial movement within said internal bore andhaving an axially inner side and an axially outer side, a first gripperring held in a fixed axial position between said axially outer side ofsaid first spacer bushing and said axially inner side of said secondspacer bushing, said first gripper ring having non-retractable gripperteeth with inner edges protruding inwardly into said internal boresufficient to engage the tube when positioned within said internal bore,and a second gripper ring held in a fixed axial position adjacent saidaxially outer side of said second spacer bushing, said second gripperring having non-retractable gripper teeth with inner edges protrudinginwardly into said internal bore sufficient to engage the tube whenpositioned within said internal bore.
 14. A coupling for holding a tubetherein, comprising: a housing having an internal bore with acircumferential side wall, a seal in said internal bore in fluid-tightengagement with said housing and positioned for fluid-tight engagementwith the tube when positioned within said internal bore, a non-movablespacer bushing retained against axial movement within said internal boreand having an axially inner side and an axially outer side, a firstgripper ring located axially outward of said seal and held in a fixedaxial position adjacent said axially inner side of said spacer bushing,said first gripper ring having non-retractable gripper teeth with inneredges protruding inwardly into said internal bore sufficient to engagethe tube when positioned within said internal bore, and a second gripperring held in a fixed axial position adjacent said axially outer side ofsaid spacer bushing, said second gripper ring having non-retractablegripper teeth with inner edges protruding inwardly into said internalbore sufficient to engage the tube when positioned within said internalbore.
 15. The coupling of claim 14 wherein said spacer bushing has aninterior wall defining an aperture sized and positioned to receive thetube therethrough when the tube is positioned within said internal bore,said gripper teeth of said first gripper ring protrude inwardly beyondsaid interior wall of said spacer bushing in position to engage the tubewhen positioned within said aperture of said spacer bushing withoutadjustment of the position of said spacer bushing or first gripper ringwithin said internal bore, and said gripper teeth of said second gripperring protrude inwardly beyond said interior wall of said spacer bushingin position to engage the tube when positioned within said aperture ofsaid spacer bushing without adjustment of the position of said spacerbushing or second gripper ring within said internal bore.
 16. A couplingfor holding a tube therein, comprising: a housing having an internalbore with a circumferential side wall, said internal bore being sized toreceive the tube therein, a non-movable spacer bushing retained againstaxial movement within said internal bore and having an axially innerside and an axially outer side, a first gripper ring held in a fixedaxial position adjacent said axially inner side of said spacer bushing,said first gripper ring having non-retractable gripper teeth with inneredges protruding inwardly into said internal bore sufficient to engagethe tube when positioned within said internal bore, and a second gripperring held in a fixed axial position adjacent said axially outer side ofsaid spacer bushing, said second gripper ring having non-retractablegripper teeth with inner edges protruding inwardly into said internalbore sufficient to engage the tube when positioned within said internalbore.
 17. The coupling of claim 16 wherein said first gripper ring has aperipheral portion with said gripper teeth thereof extending inwardlytherefrom and said second gripper ring has a peripheral portion withsaid gripper teeth thereof extending inwardly therefrom, said peripheralportions of said first and second gripper rings being retained againstaxial movement within said internal bore.
 18. The coupling of claim 17further including an end bushing attached to said housing and retainingsaid peripheral portions of said first and second spacer bushingsagainst axial movement within said internal bore.
 19. The coupling ofclaim 17 further including an end bushing attached to said housing andapplying an axially inward force to retain said peripheral portions ofsaid first and second spacer gripper rings against axial movement withinsaid internal bore toward said end bushing.